windows checkpoint

src/synth/AudioEngine.cpp

@@ -0,0 +1,73 @@
+
+#include "AudioEngine.h"
+
+#include <iostream>
+#include <math.h>
+
+AudioEngine::AudioEngine() {
+    if(audio_.getDeviceCount() < 1) {
+        throw std::runtime_error("No audio devices found");
+    }
+}
+
+AudioEngine::~AudioEngine() {
+    stop();
+}
+
+bool AudioEngine::start() {
+
+    RtAudio::StreamParameters params;
+    params.deviceId = audio_.getDefaultOutputDevice();
+    params.nChannels = 1;
+    params.firstChannel = 0;
+
+    RtAudio::StreamOptions options;
+    options.flags = RTAUDIO_MINIMIZE_LATENCY;
+
+    try {
+        audio_.openStream(&params, nullptr, RTAUDIO_FLOAT32, sampleRate_, &bufferFrames_, &AudioEngine::audioCallback, this, &options);
+        audio_.startStream();
+    } catch(RtAudioError& e) {
+        std::cerr << e.getMessage() << std::endl;
+        return false;
+    }
+
+    std::cout << "sample rate: " << sampleRate_ << "  buffer frames: " << bufferFrames_ << std::endl;
+    return true;
+
+}
+
+void AudioEngine::stop() {
+
+    if(audio_.isStreamRunning()) audio_.stopStream();
+    if(audio_.isStreamOpen()) audio_.closeStream();
+}
+
+void AudioEngine::setFrequency(float freq) {
+    targetFreq_.store(freq, std::memory_order_relaxed);
+}
+
+int32_t AudioEngine::audioCallback( void* outputBuffer, void*, uint32_t nFrames, double, RtAudioStreamStatus status, void* userData) {
+    
+    if (status) std::cerr << "Stream underflow!" << std::endl;
+
+    return static_cast<AudioEngine*>(userData)->process(static_cast<float*>(outputBuffer), nFrames);
+}
+
+int32_t AudioEngine::process(float* out, uint32_t nFrames) {
+    const float sr = static_cast<float>(sampleRate_);
+    float target = targetFreq_.load(std::memory_order_relaxed);
+    float freqStep = (target - currentFreq_) / nFrames;
+
+    for (uint32_t i = 0; i < nFrames; ++i) {
+        currentFreq_ += freqStep;
+
+        float phaseInc = 2.0f * M_PI * currentFreq_ / sr;
+        out[i] = std::sin(phase_);
+
+        phase_ += phaseInc;
+        if (phase_ > 2.0f * M_PI) phase_ -= 2.0f * M_PI;
+    }
+
+    return 0;
+}

src/synth/AudioEngine.h

@@ -0,0 +1,31 @@
+
+#pragma once
+
+#include <RtAudio.h>
+#include <stdint.h>
+#include <atomic>
+
+class AudioEngine {
+
+public:
+    AudioEngine();
+    ~AudioEngine();
+
+    bool start();
+    void stop();
+
+    void setFrequency(float freq);
+
+private: 
+    static int32_t audioCallback(void* outputBuffer, void* inputBuffer, uint32_t nFrames, double streamTime, RtAudioStreamStatus status, void* userData);
+    int32_t process(float* out, uint32_t nFrames);
+
+    RtAudio audio_;
+    uint32_t sampleRate_ = 44100;
+    uint32_t bufferFrames_ = 256;
+
+    std::atomic<float> targetFreq_{ 400.0f };
+    float currentFreq_ = 440.0f;
+    float phase_ = 0.0f;
+
+};